.\"	$OpenBSD: sensor_attach.9,v 1.12 2014/01/21 03:15:46 schwarze Exp $
.\"
.\" Copyright (c) 2006 Michael Knudsen <mk@openbsd.org>
.\" Copyright (c) 2006 Constantine A. Murenin <cnst+openbsd@bugmail.mojo.ru>
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.Dd $Mdocdate: January 21 2014 $
.Dt SENSOR_ATTACH 9
.Os
.Sh NAME
.Nm sensor_attach ,
.Nm sensor_detach ,
.Nm sensor_find ,
.Nm sensordev_install ,
.Nm sensordev_deinstall ,
.Nm sensordev_get ,
.Nm sensor_task_register ,
.Nm sensor_task_unregister
.Nd sensors framework
.Sh SYNOPSIS
.In sys/sensors.h
.Ft void
.Fn "sensordev_install" "struct ksensordev *sensdev"
.Ft void
.Fn "sensordev_deinstall" "struct ksensordev *sensdev"
.Ft struct ksensordev *
.Fn "sensordev_get" "int devnum"
.Pp
.Ft void
.Fn "sensor_attach" "struct ksensordev *sensdev" "struct ksensor *sens"
.Ft void
.Fn "sensor_detach" "struct ksensordev *sensdev" "struct ksensor *sens"
.Ft struct ksensor *
.Fn "sensor_find" "int devnum" "enum sensor_type stype" "int numt"
.Pp
.Ft struct sensor_task *
.Fn "sensor_task_register" "void *arg" "void (*func)(void *)" "int period"
.Ft void
.Fn "sensor_task_unregister" "struct sensor_task *st"
.Sh DESCRIPTION
The
sensors
framework API provides a mechanism for manipulation of hardware sensors
that are available under the
.Va hw.sensors
.Xr sysctl 8
tree.
.Pp
.Fn sensor_attach
adds the sensor specified by the
.Fa sens
argument to the sensor device specified by the
.Fa sensdev
argument.
.Fn sensor_detach
can be used to remove sensors previously added by
.Fn sensor_attach .
.Pp
.Fn sensordev_install
registers the sensor device specified by the
.Fa sensdev
argument so that all sensors that are attached to the device become
accessible via the sysctl interface.
.Fn sensordev_deinstall
can be used to remove sensor devices previously registered by
.Fn sensordev_install .
.Pp
.Fn sensordev_get
takes ordinal number
.Fa devnum
specifying a sensor device and
returns a pointer to the corresponding
.Vt struct ksensordev ,
or
.Dv NULL
if no such sensor device exists.
.Pp
.Fn sensor_find
takes ordinal number
.Fa devnum
specifying a sensor device, sensor type
.Fa stype
and ordinal number of sensor of such type
.Fa numt ,
and returns a pointer to the corresponding
.Vt struct ksensor ,
or
.Dv NULL
if no such sensor exists.
.Fn sensor_find
will always return
.Dv NULL
if the corresponding sensor devices are not registered by
.Fn sensordev_install .
.Pp
Drivers are responsible for retrieving, interpreting, and normalising
sensor values and updating the sensor struct periodically.
If the driver needs process context, for example to sleep, it can
register a task with the sensor framework.
.Pp
.Fn sensor_task_register
is used to register a periodic task to update sensors.
The
.Fa func
argument is a pointer to the function to run with an interval of
.Fa period
seconds.
The
.Fa arg
parameter is the argument given to the
.Fa func
function.
.Fn sensor_task_unregister
ensures that the task specified by the
.Fa st
argument is no longer running, and then removes it from the queue.
.Pp
All the functions in the sensor framework must be called during
.Xr autoconf 9
or from a process context.
Additionally,
.Fn sensor_task_unregister
must not be called from the sensor task that it is about to remove.
.Sh SEE ALSO
.Xr sysctl 8 ,
.Xr autoconf 9
.Sh HISTORY
The sensor framework was written by
.An Alexander Yurchenko Aq Mt grange@openbsd.org
and first appeared in
.Ox 3.4 .
.An David Gwynne Aq Mt dlg@openbsd.org
later extended it for
.Ox 3.8 .
.An Constantine A. Murenin Aq Mt cnst+openbsd@bugmail.mojo.ru
extended it even further by introducing the concept of sensor devices in
.Ox 4.1 .
